Update Ember to 1.3.0, Ember-Data to 1.0.0-beta.6
Change code to be more idiomatic ember

 * Focus new-todo input on load
 * Use CP's for reamining and completed
 * Add pluralize helper, remove html from controller
 * Add TodoController.removeTodo method
 * We want to avoid debouncing a call to `send`, so we make `removeTodo`
   a method on the controller, and have the `removeTodo` *action* simply
   call that method.
 * Move Todo auto-save from model into controller